1. Field of the Invention
The present invention relates to a heat-insulating transparent PVC sheet, and more particularly, to a heat-insulating transparent PVC sheet having inorganic heat-insulating particles uniformly dispersed inside and made by a non-coating process.
2. Description of the Related Art
As shown in FIG. 1, a conventional heat-insulating transparent PVC sheet 10 allows visible light to pass and cuts off infrared, and is generally pasted on the glass of buildings or cars for providing a heat-insulating effect and transparency to meet visual requirement.
However, the conventional heat-insulating transparent PVC sheet 10 does not cut off the ultra-violet well. Therefore, an UV absorbent is generally added in the PVC sheet then pasted on the glass of buildings or cars for providing an effect of cutting-off ultra-violet and thereby human bodies are protected from the damage of ultra-violet.
The processes of making conventional heat-insulating transparent PVC sheets include a dry-coating process and a wet-coating process. In both processes, a heat-insulating layer is coated on a plastic substrate and then a heat-insulating transparent sheet is produced.
As shown in FIG. 1, a heat-insulating transparent sheet 10 made by the dry-coating process has a metal, metallic oxide or inorganic material 12 uniformly attached on a plastic substrate 11 by a vacuum sputtering or evaporating process as a heat-insulating layer.
As shown in FIG. 2, in a heat-insulating transparent sheet 20 made by the wet-coating process, heat-insulating inorganic particles 22 are distributed uniformly in an appropriate resin 23 and solvent to form a coating liquid with appropriate viscosity for coating on a plastic substrate 21. After drying to remove the solvent, the inorganic particles 22 and the resin 23 become a heat-insulating layer attached on the plastic substrate 21.
However, two processes are needed in the above either the dry-coating process or the wet-coating process requires two procedures. One is making the plastic substrate and the other is coating the plastic substrate with a heat-insulating layer. Therefore, the drawbacks of the dry-coating and wet-coating processes of conventional heat-insulating sheets comprise complicated procedures, expensive equipments and slow production speed. Besides, environmental issues of waste solvents exist in the wet-coating processes.